The overall objective of the current Grant, CA 25584-01 RAD, was to determine whether a radioiodinated antibody to carcinoembryonic antigen (CEA) could detect and localize tumors by external photoscanning. Based upon our findings in more than 200 patients, we have concluded that his method of "radioimmunodetection" is a successful and most promising new technology for in vivo tumor radiolocalization. 1. Both primary and secondary epithelial tumors of diverse histopathology could be localized successfully by external scintillation imaging after administration of the appropriate radiolabeled antibody preparation. Radioiodinated normal goat IgG does not yield comparable results. 2. Such tumor demonstrations correlate very well with other diagnostic findings, and occasionally detected tumors not demonstrable by other techniques. 3. Tumors not known to contain appropriate antigen (CEA or (AFP) do not show localization of abnormal radioactivity. 4. Very high titers of circulating antigen do not appear to prevent tumor radiolocalization by the radiolabeled antibody to this antigen. 5. In the majority of studies, the subtraction technology developed in this study is essential for accurate localization of tumors. 6. At the present time, the resolution of the method appears to be 2 cm-diameter tumors. The purpose of the proposed supplement is to confirm and extend these findings at this and at a minimum of five other medical centers. The main objective is to determine the clinical feasibility and utility of this new method of cancer radioimmunodetection, using our own prepared radiolabeled anti-CEA IgG, in a number of specific cancer types and stages.